Si (Silicon) and Al (Aluminum) content is specified in ISO 8217:2010. From 25 to 60 mg/kg total Al and Si are permitted in marine fuel dependent on its type.

X-ray fluorescence method provides Al and Si content determination with minimum sample preparation. Definite mass of sample material is filtrated through filter (membrane filter with pores diameter n*0,1 micron). To improve filtration the sample material may be diluted by hydrocarbon solvent. Catalyst particles stay on the filter; the filter is dried and analyzed. The obtained amount of Al and Si is divided by the sample mass (in g), so Al and Si concentration is obtained.

The method sensitivity is the first tenth parts of microgram per filter. So 2 grams of the sample material is sufficient for two concurrent measurements.